1. Field of the Invention
The present invention relates generally to architectural paint colors and, specifically, to an architectural paint color matching and coordinating system.
2. Description of the Related Art
Architectural paint (“house paint”) is commonly provided in various colors. Paint color display systems have been developed to display various paint color samples to assist consumers in selecting paint colors. Such systems typically involve a display board, pamphlet, or book having ink-based or paint color samples.
Paint colors are sometimes referenced with respect to systems for arranging and describing color, generally referred to as color-order systems. One well-known color-order system is the Munsell system. According to the Munsell system, colors are characterized by three attributes: hue, value, and chroma. Hue is the attribute of color which is commonly described by words such as “red,” “yellow,” “green,” “blue,” “purple,” etc. Value is the attribute of color which is described by the words “light,” “dark,” etc. Chroma is the attribute of color which is described by the words “bright,” “dull,” etc. For example, the colors of a tomato and a brick may be equal in hue and value, yet the colors are not identical. The difference is that the tomato is brighter, having a higher chroma.
Munsell color space is a three-dimensional space including and describing visual relationships between colors. This color space is based on a collection of actual physical samples arranged so that adjacent samples represent distinct intervals of visual color perception. Although based on physical samples, Munsell color space is theoretically capable of describing all possible colors. According to the Munsell system, color space is described with respect to three dimensions: hue, value, and chroma. Theoretically, the Munsell location of every possible color can be described by three coordinates, corresponding to the hue, value, and chroma of the given color. Although in theory Munsell color space is capable of describing all colors, it is understood that it may not be possible to create physical samples of all of the colors which could theoretically fit within Munsell color space. In particular, not all theoretical colors within the perceived Munsell color space can be made into paints.
Within Munsell color space, a vertical axis, known as the value axis, represents color value. In other words, the value (lightness/darkness) of color is determined by the vertical position within color space. Color becomes lighter as the vertical position increases. The hue of color is determined by the angular position about the vertical value axis. The various hues, i.e., shades of red, yellow, green, blue, purple, etc., are represented by vertical planes extending radially from the value axis. Moreover, every angular position about the axis, from 0° to 360°, represents a different hue. The chroma (brightness/dullness) of color is determined by the radial distance from the value axis. Color is dull (gray) near the axis and becomes brighter, or more “chromatic,” as the radial distance from the value axis increases.
The Munsell system is one of a number of color-order systems based on actual physical samples. Another class of color-order systems are not based on physical samples. One of the most important of these systems is the CIE System (Commission International de l'Eclairage or International Commission on Illumination). The premise of the CIE System is that the stimulus for color is provided by a proper combination of a source of light, an object, and an observer. The CIE System describes color with reference to a standard source of illumination and a standard observer.
One widely used non-linear transformation of the CIE System is CIELAB, an opponent-type space in which color is described by three coordinates L, a, and b. In CIELAB space, L is the lightness of color (similar to Munsell value), a is a redness-greenness coordinate, and b is a yellowness-blueness coordinate.